Fixed UnicodeDecodeError on get_name and get_description methods

If you try to use non-ascii encoded stiring in docstrings to your views. Here is a sample:

```python
# -*- coding: utf-8 -*-

@api_view(('GET',))
def api_root(request, format=None):
    """ 
    Проверка
    """
    ...
```

You'll get a `UnicodeDecodeError` on your browsable api page:
```
Traceback (most recent call last):
  File "/Users/wronglink/Src/django-rest-framework/rest_framework/response.py", line 44, in rendered_content
    return renderer.render(self.data, media_type, context)
  File "/Users/wronglink/Src/django-rest-framework/rest_framework/renderers.py", line 437, in render
    description = self.get_description(view)
  File "/Users/wronglink/Src/django-rest-framework/rest_framework/renderers.py", line 407, in get_description
    return view.get_description(html=True)
  File "/Users/wronglink/Src/django-rest-framework/rest_framework/views.py", line 111, in get_description
    description = _remove_leading_indent(description)
  File "/Users/wronglink/Src/django-rest-framework/rest_framework/views.py", line 35, in _remove_leading_indent
    for line in content.splitlines()[1:] if line.lstrip()]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 4: ordinal not in range(128)
```

It could be fixed by unicode docstring, but django has it's own unicode forcing util, that will do most of the work.

P.S.
BTW isn't that a mistake that `rest_framework.renderers.BrowsableAPIRenderer.get_name` method returns `view.__doc__` (not something like `view.__class__.__name__` as `rest_framework.views.APIView.get_name` does)?